%0 Journal Article %J Journal of Computational and Graphical Statistics %D 1999 %T Robustness of Tail Index Estimation %A Hsieh,Ping-Hung %K Supply Chain %X The implementation of the Hill estimator, which estimates the heaviness of the tail of a distribution, requires a choice of the number of extreme observations in the tails, $r$, from a sample of size $n$, where $2 \leq r+1 \leq n$. This article is concerned with a robust procedure of choosing an optimal $r$. Thus, an estimation procedure, $\delta_s$, based on the idea of spacing statistics, $H^{(r)}$, is developed. The proposed decision rule for choosing $r$ under the squared error loss is found to be a simple function of the sample size. The proposed rule is then illustrated across a wide range of data, including insurance claims, currency exchange rate returns, and city size. %B Journal of Computational and Graphical Statistics %V 8 %P 318-332 %8 1999 %G eng %N 2 %2 a %4 646823936 %$ 646823936